Method for preparing polysulfone resin by staged polymerization

Abstract

The present application relates to the technical field of polymer material preparation, and specifically relates to a method for preparing a polysulfone resin by staged polymerization. The present application provides a novel staged polymerization method for a polysulfone resin. A polymerization reaction is divided into a pre-polymerization reaction and a polymerization reaction after desalination; the pre-polymerization reaction employs a phenolic monomer excess mode and a halogenated monomer excess mode; and the phenolic monomer and the halogenated monomer complete a salt formation reaction during primary polymerization, and then desalination is carried out; in this case, the viscosity is low, so that salts in a prepolymer can be separated out more easily. Thus, the problem of being unable to effectively remove salts and small molecule polymers contained in a high molecular polymer due to an increased resin viscosity after a polysulfone resin prepared by a one-step synthesis method forms the high-molecular polymer is solved, and the quality of the polysulfone resin is improved; moreover, after the salts are removed, a polymerization system approaches a homogeneous phase, thereby greatly increasing the reaction rate and realizing controllable polymerization of an ultra-high molecular weight polymer without occurrence of cross-linked implosion.

Description

A method for preparing polysulfone resin by segmented polymerization

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 15, 2023, with application number CN202311526518.4 and invention name “A method for preparing polysulfone resins by segmented polymerization”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of polymer material preparation, and specifically relates to a method for preparing polysulfone resin by staged polymerization. Background Art

[0003] Currently, the most advanced production process for polysulfone polymers is a one-step synthesis method. The main raw materials, 4,4'-dichlorodiphenyl sulfone (halogenated monomer), a phenolic polymerization monomer, and an alkali metal salt (such as potassium carbonate), are polymerized in a solvent. Common solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. After polymerization, water, ethanol, or methanol is used as a precipitant to separate the polysulfone from the polymer solution. The separated polysulfone is then purified, dried, granulated, and packaged to produce the polysulfone product. However, this one-step synthesis method produces polysulfone resins, resulting in high molecular weight polymers and high viscosity. This makes it difficult to effectively remove salts and small polymers contained within the polymer, affecting product quality. Furthermore, the presence of salts in the polymerization system makes the system heterogeneous, which reduces the frequency of intermolecular collisions during the polymerization reaction, affecting the reaction rate and preventing the polymerization of ultrahigh molecular weight polysulfone products.

[0004] Summary of the Invention

[0005] In view of this, the present application aims to provide a method for preparing polysulfone resins by staged polymerization. This method utilizes a staged polymerization process to prepare polysulfone resins, which contain fewer impurities such as salts and small-molecule polymers and have a low product haze value. Furthermore, this staged polymerization process can produce ultrahigh molecular weight polysulfone products.

[0006] In order to achieve the above-mentioned invention objectives, this application provides the following technical solutions:

[0007] The present application provides a method for preparing a polysulfone resin by staged polymerization, comprising the following steps:

[0008] A first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent are mixed to perform a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3; the first halogenated monomer contains a sulfone group;

[0009] A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance, and a second solvent are mixed to perform a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6; the second halogenated monomer contains a sulfone group;

[0010] The first prepolymer system and the second prepolymer system are desalted and then subjected to polymerization reaction to obtain the polysulfone resin.

[0011] Preferably, the first halogenated monomer and the second halogenated monomer independently include 4,4'-dichlorodiphenyl sulfone and / or 4,4'-difluorodiphenyl sulfone.

[0012] Preferably, the first phenolic monomer and the second phenolic monomer independently include one or more of bisphenol A, bisphenol S and 4,4′-biphenyl diphenol.

[0013] Preferably, the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.8-5.3:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.8-5.3.

[0014] Preferably, the molar ratio of the total amount of halogenated monomers to the total amount of phenolic monomers is 1-1.05:1-1.05, the halogenated monomers include a first halogenated monomer and a second halogenated monomer, and the phenolic monomers include a first phenolic monomer and a second phenolic monomer.

[0015] Preferably, the first alkali metal-containing substance and the second alkali metal-containing substance independently comprise alkali metal hydroxides and / or alkali metal salts.

[0016] Preferably, the molar ratio of the first alkali metal-containing substance to the first halogenated monomer and the molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently 1.01 to 1.51:1.

[0017] Preferably, the temperature of the first prepolymerization reaction and the second prepolymerization reaction are independently 180-200° C., and the time is independently 2-3 hours.

[0018] Preferably, the polymerization reaction temperature is 220-250° C., and the time is 2-8 hours.

[0019] Preferably, the polymerization reaction temperature is 230-250° C., and the time is 4-8 hours.

[0020] The present invention also provides a device for preparing polysulfone resins by staged polymerization, comprising a first polymerization kettle, a second polymerization kettle connected in parallel with the first polymerization kettle, a filtering device connected to the discharge ports of the first polymerization kettle and the second polymerization kettle, and a third polymerization kettle connected to the discharge port of the filtering device.

[0021] Compared with the prior art, this application has the following beneficial effects:

[0022] The present application provides a new staged polymerization method for polysulfone resins, which divides the polymerization reaction into two parts: a prepolymerization reaction (including a first prepolymerization reaction and a second prepolymerization reaction) and a polymerization reaction after desalting. The prepolymerization reaction adopts two methods: an excess of phenolic monomer and an excess of halogenated monomer. Controlling the degree of excess of phenolic monomer and the excess of halogenated monomer respectively can control the increase in viscosity of the prepolymer system (including the first prepolymer system and the second prepolymer system). The phenolic monomer and the halogenated monomer complete the salt-forming reaction in the prepolymerization stage and then undergo desalting treatment. At this time, the viscosity is relatively low. At a temperature of 200°C, the viscosity range is 5 to 20 mPa·s, which can make it easier to separate the salt in the prepolymer. After the desalting treatment is performed at this stage, the overall desalting effect is greatly improved, which solves the problem of preparing polysulfone resins by a one-step synthesis method. After the polysulfone resin forms a high molecular weight polymer, the resin viscosity becomes large (700 to 1200 mPa·s), and the salts and small molecular polymers contained in the high molecular weight polymer cannot be effectively removed, thereby improving the product quality of the polysulfone resin.

[0023] Furthermore, after the salts are removed from the prepolymer system of the present application (including the first prepolymer system and the second prepolymer system), the polymerization system approaches a homogeneous phase, the frequency of intermolecular collisions is high, the reaction rate can be greatly improved, and the temperature and time of the polymerization reaction can be controlled at the same time, so that the controlled polymerization of ultra-high molecular weight polymers can be achieved without the occurrence of cross-linking explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] FIG1 is a schematic diagram of the apparatus for preparing polysulfone resin by staged polymerization in Example 1. DETAILED DESCRIPTION

[0026] The present application provides a method for preparing a polysulfone resin by staged polymerization, comprising the following steps:

[0027] A first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent are mixed to perform a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3; the first halogenated monomer contains a sulfone group;

[0028] A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance, and a second solvent are mixed to perform a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6; the second halogenated monomer contains a sulfone group;

[0029] The first prepolymer system and the second prepolymer system are desalted and then subjected to polymerization reaction to obtain the polysulfone resin.

[0030] In this application, unless otherwise specified, the materials and equipment used are commercially available products in this field.

[0031] In the present application, a first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent are mixed to perform a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3;

[0032] A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent are mixed to perform a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6.

[0033] In the present application, the first halogenated monomer and the second halogenated monomer are preferably aromatic dihalogen sulfone monomers, and the aromatic dihalogen sulfone monomers preferably include 4,4′-dichlorodiphenyl sulfone (DCPDS) and / or 4,4′-difluorodiphenyl sulfone (DFDPS), and the first halogenated monomer and the second halogenated monomer are preferably 4,4′-dichlorodiphenyl sulfone.

[0034] In the present application, the first phenolic monomer and the second phenolic monomer are preferably aromatic dihydroxy monomers, and the aromatic dihydroxy monomer preferably includes one or more of bisphenol A, bisphenol S and 4,4′-biphenol, and the first halogenated monomer and the second halogenated monomer are preferably 4,4′-biphenol.

[0035] In the present application, the molar ratio of the first halogenated monomer to the first phenolic monomer is preferably 3.8 to 5.3:3, more preferably 4:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is preferably 3:3.8 to 5.3, more preferably 3:4. The present application controls the degree of excess of one monomer in the prepolymerization reaction (including the first prepolymerization reaction and the second prepolymerization reaction), which can control the increase in the viscosity of the prepolymer system (including the first prepolymer and the second prepolymer), which is beneficial to subsequent desalination.

[0036] In the present application, the molar ratio of the total amount of halogenated monomers to the total amount of phenolic monomers is preferably 1 to 1.05:1 to 1.05, more preferably 1 to 1.03:1, the halogenated monomers include a first halogenated monomer and a second halogenated monomer, and the phenolic monomers include a first phenolic monomer and a second phenolic monomer.

[0037] In the present application, the first alkali metal-containing substance and the second alkali metal-containing substance are independently preferably alkali metal hydroxides and / or alkali metal salts, the alkali metal hydroxides preferably include sodium hydroxide and / or potassium hydroxide, and the alkali metal salts preferably include one or more of sodium carbonate, potassium carbonate, potassium bicarbonate, sodium bicarbonate and sodium hydride.

[0038] In the present application, the molar ratio of the first alkali metal-containing substance to the first halogenated monomer and the molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently preferably 1.01 to 1.51:1, more preferably 1.1:1.

[0039] In the present application, the first solvent and the second solvent are preferably aprotic polar solvents, and the aprotic polar solvent preferably includes one or more of dimethyl sulfoxide (DMSO), dimethyl sulfone, diphenyl sulfone (DPS), diethyl sulfoxide, cyclopentane, tetrahydrothiophene-1-monoxide, N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and 1,3-dimethyl-2-imidazolidinone (DMI).

[0040] In the present application, the temperature of the first prepolymerization reaction and the second prepolymerization reaction is independently preferably 180 to 200° C., more preferably 190° C., and the time is independently preferably 2 to 3 hours. During the first prepolymerization reaction and the second prepolymerization reaction, the hydroxyl end groups in the phenolic monomer react with an alkali metal-containing substance (such as sodium carbonate) under an alkaline environment, and the alkali metal salt end groups of the generated phenolic monomer attack the halogen element of the halogenated monomer at high temperature to form a preliminary polymer base segment, and the alkali metal and the halogen element form a halogenated alkali metal salt that falls off.

[0041] In the present application, the end groups of the prepolymers in the first prepolymer system are halogen elements, and the end groups of the prepolymers in the second prepolymer system are phenolate end groups; the viscosities of the first prepolymer system and the second prepolymer system are preferably 5 to 20 mPa·s.

[0042] After obtaining the first prepolymer and the second prepolymer, the present application desalts the first prepolymer system and the second prepolymer system and then performs a polymerization reaction to obtain the polysulfone resin.

[0043] In the present application, the desalination method is preferably hot filtration, the temperature of the hot filtration is preferably 160-190°C, and the hot filtration device is preferably a metal titanium rod filter. The present application uses hot filtration for desalination. Within the temperature range of hot filtration described in the present application, the polymer obtained by the prepolymerization reaction has good solubility and can more thoroughly remove the halogenated alkali metal salt.

[0044] The present application preferably performs desalting after mixing the first prepolymer and the second prepolymer, and preferably further comprises adding a capping agent after the desalting, and the capping agent preferably comprises a halogenated monomer and / or a phenolic monomer, the halogenated monomer is preferably of the same type as the first halogenated monomer or the second halogenated monomer, and the phenolic monomer is preferably of the same type as the first phenolic monomer or the second phenolic monomer, which will not be repeated here, and the amount of the capping agent is preferably 1% of the total amount of the first halogenated monomer and the second halogenated monomer, or 2% of the total amount of the first phenolic monomer and the second phenolic monomer.

[0045] In the present application, the polymerization reaction temperature is preferably 220-250° C., more preferably 230-250° C., and more preferably 240° C., and the polymerization time is preferably 2-8 h, more preferably 4-8 h, and more preferably 6 h.

[0046] The present application obtains a polymer mixture after the polymerization reaction. After obtaining the polymer mixture, the present application preferably further comprises discharging, dispersing, crushing, washing and drying the polymer mixture in sequence to obtain the polysulfone resin.

[0047] The present application has no special requirements for the method of dispersing and pulverizing the material, and the commonly used method by those skilled in the art can be adopted. The reagent used for dispersing the material is preferably water, and the polysulfone resin is precipitated in the water during the dispersing process.

[0048] In the present application, the washing reagent is preferably pure water, the water-to-material mass ratio of the washing is preferably 8:1, the number of washing times is preferably 8 times, and the washing can remove salt.

[0049] In the present application, the drying temperature is preferably 150-170° C., more preferably 160° C., and the drying time is preferably 6-8 h, more preferably 7 h.

[0050] The present invention also provides a device for preparing polysulfone resins by staged polymerization, comprising a first polymerization kettle, a second polymerization kettle connected in parallel with the first polymerization kettle, a filtering device connected to the discharge ports of the first polymerization kettle and the second polymerization kettle, and a third polymerization kettle connected to the discharge port of the filtering device.

[0051] Figure 1 is a schematic diagram of the apparatus for preparing polysulfone resins by staged polymerization in an embodiment of the present application. The apparatus comprises a first polymerization kettle R1, a second polymerization kettle R2 connected in parallel with the first polymerization kettle R1, a filtration device connected to the discharge ports of the first and second polymerization kettles R1 and R2, and a third polymerization kettle R3 connected to the discharge port of the filtration device. The method for preparing polyethersulfone resins using this apparatus includes: performing preliminary polymerization (prepolymerization) in the R1 and R2 polymerization kettles, desalting the product through the filtration device, and then subjecting the filtered and desalted product to a high-temperature (220-250°C) polymerization reaction in the R3 reactor to produce the polysulfone resin.

[0052] In order to further illustrate the present application, the method for preparing polysulfone resin by staged polymerization of the present application is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present application.

[0053] Example 1

[0054] Using 4,4'-dichlorodiphenyl sulfone and 4,4'-biphenyldiphenol, the reaction is carried out according to multi-stage polymerization:

[0055] In the initial polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-biphenol in the polymerization reactor R1 was 4:3: 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 5.61 kg of 4,4'-biphenol and 4.7 kg of sodium carbonate were added to the polymerization reactor R1, with 44.73 kg of sulfolane as the solvent;

[0056] In the initial polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-biphenol in the polymerization reactor R2 was 3:4: 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 7.48 kg of 4,4'-biphenol and 4.7 kg of sodium carbonate were added to the polymerization reactor R2, with 41.73 kg of sulfolane as the solvent;

[0057] The initial polymerization in both reactors R1 and R2 was conducted at 180°C for a salt-forming reaction, which lasted for 3 hours. The initial polymerization products in reactors R1 and R2 were filtered through a filter to remove salt, then mixed in reactor R3 for a high-temperature polymerization reaction. 1% of 4,4'-dichlorodiphenyl sulfone (based on the total amount in reactors R1 and R2) was added to reactor R3 for end-capping. The mixture was stirred and polymerized at 220°C for 5 hours. The entire polymerization process was carried out under an inert gas (nitrogen) atmosphere. After completion of the polymerization, the materials were discharged for dispersion, crushed, washed (eight times with ultrapure water at a water-to-material ratio of 8:1), and dried to obtain the finished polymer, polyphenylsulfone resin powder.

[0058] The polysulfone product obtained in Example 1 had a haze of 1.1 and a content of small molecular polymers of 40 ppm.

[0059] Example 2

[0060] Using 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone, the reaction is carried out according to multi-stage polymerization:

[0061] In the initial polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization reactor R1 was 4:3: 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 7.5 kg of 4,4-dihydroxydiphenyl sulfone and 4.7 kg of sodium carbonate were added to the polymerization reactor R1, with 50.388 kg of sulfolane as the solvent;

[0062] In the initial polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization reactor R2 was 3:4: 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 10 kg of 4,4-dihydroxydiphenyl sulfone and 4.7 kg of sodium carbonate were added to the polymerization reactor R2, with 49.275 kg of sulfolane as the solvent;

[0063] The initial polymerization in both reactors R1 and R2 was conducted at 180°C for a salt-forming reaction, with the salt-forming stage completed after 3 hours of polymerization. The initial polymerization products in reactors R1 and R2 were filtered through a filter to remove salt, then mixed in reactor R3 for a high-temperature polymerization reaction. 2% of 4,4-dihydroxydiphenyl sulfone (based on the total amount in reactors R1 and R2) was added to reactor R3 for end-capping. The mixture was stirred and polymerized at 220°C for 5 hours. The entire polymerization process was carried out under an inert gas (nitrogen) atmosphere. After completion of the polymerization, the materials were discharged for dispersion, crushed, washed (eight times with ultrapure water at a water-to-material ratio of 8:1), and dried to obtain the finished polymer, polyphenylsulfone resin powder.

[0064] The polysulfone product obtained in Example 2 had a haze of 1.5 and a content of small molecular polymers of 50 ppm.

[0065] Example 3

[0066] 4,4'-Dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone were used to prepare an ultra-high molecular weight polymer by multi-stage polymerization. The polymerization reaction was carried out at a solid content of 35%:

[0067] In the initial polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization reactor R1 was 4:3: 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 7.504 kg of 4,4-dihydroxydiphenyl sulfone and 7.4 kg of sodium carbonate were added to the polymerization reactor R1, with 31.2 kg of sulfolane as the solvent;

[0068] In the initial polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-dihydroxydiphenyl sulfone in the polymerization reactor R2 was 3:4: 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 10.048 kg of 4,4-dihydroxydiphenyl sulfone and 7.4 kg of sodium carbonate were added to the polymerization reactor R2, with 30.59 kg of sulfolane as the solvent;

[0069] The initial polymerization in both reactors R1 and R2 was conducted at 180°C, with a solids content of 35%. The salt formation stage was completed after 3 hours of polymerization. The initial polymerization products in reactors R1 and R2 were filtered through a filtration device to remove salts, and then mixed in reactor R3 for a high-temperature polymerization reaction. The R3 reactor was stirred and polymerized at 240°C for 6 hours. The entire polymerization process was carried out under the protection of an inert gas (nitrogen). After the polymerization was completed, the materials were discharged, dispersed, crushed, washed (washed eight times with ultrapure water at a water-to-material ratio of 8:1), and dried to obtain the finished polymer polyphenylsulfone resin powder.

[0070] The weight average molecular weight of the polysulfone product obtained in Example 3 is 80w.

[0071] Comparative Example 1

[0072] 4,4'-dichlorodiphenyl sulfone and 4,4'-biphenyl diphenol were used to carry out the polymerization reaction in a one-step process:

[0073] The molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-biphenol in the polymerization kettle was 1.03:1. 11.83 kg of 4,4'-dichlorodiphenyl sulfone, 7.46 kg of 4,4'-biphenol, and 6.3 kg of sodium carbonate were added to the polymerization kettle, with 14.5 kg of sulfolane as the solvent. The polymerization reaction was carried out at 180°C for 3 hours, then the temperature was raised to 220°C and the polymerization reaction was stirred for 5 hours. The entire polymerization process was carried out under inert gas (nitrogen). After the polymerization was completed, the materials were discharged for dispersion, crushed, washed (washed eight times with ultrapure water at a water-to-material ratio of 8:1), and dried to obtain the finished polymer polyphenylsulfone resin powder.

[0074] The polysulfone product prepared in Comparative Example 1 had a haze of 5 and a content of small molecule polymers of 1000 ppm.

[0075] As shown in the examples and comparative examples, the polysulfone resin product produced by staged polymerization in this application exhibits significantly reduced haze and low-molecular-weight polymer content, significantly improving the product quality of the polysulfone resin. Furthermore, by further controlling the solids content of the feed solution, the temperature, and the time of the polymerization reaction during the polymerization process, this application has produced a polysulfone product with an ultrahigh molecular weight (800,000).

[0076] Although the above embodiments provide a detailed description of the present application, they are only part of the embodiments of the present application, not all of the embodiments. People can also obtain other embodiments based on the embodiments of the present application without creative work, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A method for preparing polysulfone resin by staged polymerization, characterized in that: The following steps are involved: A first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent are mixed to perform a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3; the first halogenated monomer contains a sulfone group; A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent are mixed for a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6; the second halogenated monomer contains a sulfone group; The first prepolymer system and the second prepolymer system are desalted and then subjected to polymerization reaction to obtain the polysulfone resin.

2. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The first halogenated monomer and the second halogenated monomer independently include 4,4'-dichlorodiphenyl sulfone and / or 4,4'-difluorodiphenyl sulfone.

3. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The first phenolic monomer and the second phenolic monomer independently include one or more of bisphenol A, bisphenol S and 4,4′-biphenol.

4. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The molar ratio of the first halogenated monomer to the first phenolic monomer is 3.8-5.3:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.8-5.

3.

5. The method for preparing polysulfone resin by staged polymerization according to claim 4, characterized in that: The molar ratio of the first halogenated monomer to the first phenolic monomer is 4:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:

4.

6. The method for preparing polysulfone resin by staged polymerization according to claim 1 or 4, characterized in that: The molar ratio of the total amount of halogenated monomers to the total amount of phenolic monomers is 1-1.05:1-1.05, the halogenated monomers include a first halogenated monomer and a second halogenated monomer, and the phenolic monomers include a first phenolic monomer and a second phenolic monomer.

7. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The first alkali metal-containing material and the second alkali metal-containing material independently include alkali metal hydroxides and / or alkali metal salts.

8. The method for preparing polysulfone resin by staged polymerization according to claim 1 or 7, characterized in that: The molar ratio of the first alkali metal-containing substance to the first halogenated monomer and the molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently 1.01 to 1.51:

1.

9. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The temperature of the first prepolymerization reaction and the second prepolymerization reaction are independently 180-200° C., and the time is independently 2-3 hours.

10. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The method further comprises adding a capping agent after the desalting.

11. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The polymerization reaction temperature is 220-250° C. and the reaction time is 2-8 hours.

12. The method for preparing polysulfone resin by staged polymerization according to claim 11, characterized in that: The polymerization reaction temperature is 230-250° C. and the reaction time is 4-8 hours.

13. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: After the polymerization reaction, the obtained polymer mixed solution is sequentially subjected to material dispersing, crushing, washing and drying to obtain the polysulfone resin.

14. A device for preparing polysulfone resin by staged polymerization, characterized in that: The invention comprises a first polymerization kettle, a second polymerization kettle connected in parallel with the first polymerization kettle, a filtering device connected with the discharge ports of the first polymerization kettle and the second polymerization kettle, and a third polymerization kettle connected with the discharge port of the filtering device.

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